TEHRAN -- Iran's government will build 10 new sites to enrich uranium, President Mahmoud Ahmadinejad said Sunday, a dramatic expansion of the country's nuclear program and one that is bound to fuel fears that it is attempting to produce a nuclear weapon.

Ahmadinejad told the official Islamic Republic News Agency that construction of at least five nuclear facilities is to begin within two months.

The surprise announcement came two days after a censure of Iran by the International Atomic Energy Agency over the Islamic republic's refusal to stop enriching uranium, a key demand of Western powers. The 35-member board of the agency also criticized Iran's construction of a second enrichment plant in Qom, southwest of Tehran.

U.S. officials reacted cautiously to the announcement. White House press secretary Robert Gibbs said that Iran's plans, if true, "would be yet another serious violation of Iran's clear obligations under multiple U.N. Security Council resolutions and another example of Iran choosing to isolate itself."

Less than a year after President Obama pledged to engage Iran, U.S. efforts at rapprochement have yielded little in return, and relations between the sides now appear to be headed toward a more confrontational phase. In a sign of growing hostility toward the West, Iran's parliament on Sunday called on Ahmadinejad's government to reduce ties with the IAEA -- a move that could limit the agency's access to Iranian nuclear sites.

Iran has insisted that its nuclear program is designed for energy production and denies that it is seeking to build a nuclear bomb. In announcing plans for the new facilities on Sunday, Ahmadinejad said his country's need for energy will grow dramatically over the next 15 years.

"We annually must produce between 250 to 300 tons of nuclear fuel," he said.

The planned expansion of Iran's nuclear program is highly ambitious; if completed, it would give the country vastly more nuclear fuel. According to a November report by the IAEA, Iran has 8,745 centrifuges to enrich uranium, but fewer than half of them are operational. It would probably take years for Iran to accomplish this goal, making it more of a symbolic announcement than a practical one. The country has not brought a single enrichment plant, Natanz, to full scale even though construction began eight years ago, and the Qom facility still has no centrifuges.

The United States and its allies, under an IAEA-backed plan, recently sought to reduce Iran's nuclear stockpile by proposing that the Islamic republic ship most of its enriched uranium abroad to be fashioned into fuel for a research reactor. Iran has rejected a central element of that proposal, instead pointing toward a counterproposal that U.S. diplomats say is a non-starter.

The resolution passed by the IAEA on Friday, which censured Iran for a "breach of its obligation" under U.N. treaties, makes it even more unlikely that the country's leaders will seek a middle ground with the West.

"We are ready to be friendly and kind toward the whole world, but at the same time we won't allow the smallest violation of the rights of the Iranian nation," Ahmadinejad said Sunday.

The head of Iran's Atomic Energy Organization, Ali Akbar Salehi, standing alongside the president, told reporters that the decisions by Iran's cabinet are a strong response to the "unacceptable actions of world powers."

Iran now voluntarily allows certain inspections, giving specified technical information and allowing permanent U.N. security cameras at its nuclear sites. Under the Non-Proliferation Treaty, which is meant to prevent the spread of nuclear weapons, it is not required to allow many checks by the U.N. nuclear agency. Some parliamentarians want Iran to abandon the agreement.

Analysts say such a move is unlikely. Nonetheless, politicians, officials and senior clerics here expressed their dismay over Friday's reprimand by the IAEA, saying Iran has gone beyond its legal requirements to prove its good intentions and calling for reducing cooperation with the agency.

"We have options ranging from complete and full cooperation to leaving the Non-Proliferation Treaty on our table," said Kazem Jalali, spokesman for the parliament's national security and foreign policy committee. "But we believe that if the West reforms its path, we can still choose the full-cooperation option."

The parliament has made similar calls in the past to reduce cooperation with the IAEA, to no avail. It has, however, regularly managed to block an update to the Non-Proliferation Treaty that would widen the atomic watchdog's inspection capabilities.

Mashallah Shamsolva'ezin, a journalist who is barred from working by the government and now advises at the Tehran-based Middle East Strategic Research Center, said both Iran and world powers, led by the United States, have little space to maneuver diplomatically. Iran, for its part, believes sanctions from the U.N. Security Council can be ignored.

"Iran's nuclear policy has always been about walking the tightrope at the edge of a cliff," he said. "But our leaders will never take actions that would jeopardize Iran's national security. For both parties, the only solution is negotiations."